The alloy contains 28% copper. What is the weight of the alloy if it contains 54 tons of copper.

From the condition we know that the alloy contains 28% copper. In order to find what is the mass of the alloy, if it contains 54 tons of copper, let’s make up and solve the proportion.

Let us denote the weight of the entire alloy as x tons and take it as 100%.

Let’s write down the proportion.

54 tons – 28%;

x tons – 100%.

54 / x = 28/100;

We need to find the unknown middle term of the proportion. The rule says that in order to find the unknown average term of the proportion, we must divide the product of the extreme terms by the known average:

x = (54 * 100) / 28 = 5400/28 = 192.86 tons is the mass of the alloy.